羧基化单壁碳纳米管-纳米金复合膜修饰电极测定己烯雌酚

通过自组装技术,制备了羧基化单壁碳纳米管-纳米金复合膜修饰玻碳电极,己烯雌酚在该修饰电极上有良好的电化学行为,于0.20V和0.135V分别出现一氧化还原峰,考察了pH、扫描速度、富集电压、富集时间等对峰电流的影响。利用差分脉冲伏安法,氧化峰峰电流与DES浓度在2.0×10~(-9)~3.0×10~(-7)mol/L范围内呈良好的线性关系,检出限为9.0×10~(-10)mol/L。方法可用于药片中己烯雌酚含量的测定。     

聚吡咯／多壁碳纳米管修饰电极对多巴胺的测定

制备了聚吡咯/多壁碳纳米管(PPy/MWNT)复合膜修饰电极。研究了神经递质多巴胺(DA)在该修饰电极上的电化学行为。实验表明,PPy/MWNT复合膜修饰电极对DA的电催化作用优于PPy修饰电极。在pH=4.10的0.2mol/L醋酸-醋酸钠缓冲溶液中,DA在该修饰电极上的CV曲线于0.31V和0.28V处出现一对灵敏的氧化还原峰,峰电位差△Ep比裸玻碳电极降低58mV,比PPy修饰电极降低28mV,峰电流显著增加。氧化峰电流ipa与DA浓度在1.0×10-4~7.8×10-8mol/L范围内呈良好的线性关系,线性回归方程为ip(μA)=0.2512 1.2300C(×10-5mol/L),相关系数r=0.9992,检出限为3.9×10-8mol/L。常见物质对DA的检测无干扰,DA注射液样品检测回收率为94%~104%。     

咖啡酸在多壁碳纳米管修饰玻碳电极上的电化学行为及其测定

制备了多壁碳纳米管(MWNT)修饰玻碳电极,并研究了咖啡酸在该电极上的电化学行为及其测定方法,与裸玻碳电极(GCE)相比,MWNT膜修饰电极(MWNT/GCE)能显著提高咖啡酸的氧化峰电流.在pH=3.29的B-R缓冲溶液中,咖啡酸在MWNT/GCE电极上出现1对准可逆的氧化还原峰,Epa=0.47 V,Epc=0.32 V,峰电流与其浓度在5.0×10-7～2.0×10-5 mol/L范围内成线性关系,检出限为5.0×10-7mol/L.实际样品测定的相对标准偏差(RSD)为0.82％(n=5),平均回收率为100.7％.MWNT膜对咖啡酸的电化学氧化有明显的催化作用.该法是一种快捷、可靠、灵敏的检测方法,可以用于咖啡酸含量的测定.     

掺杂多壁碳纳米管改性聚溴甲酚绿膜修饰电极的制备、表征与应用研究

研究了掺杂多壁碳纳米管(MWNT)改性聚溴甲酚绿膜(PBG),以不同修饰方法制备了4种修饰电极,用扫描电镜、交流阻抗及循环伏安法等对电极进行表征。结果表明:4种修饰电极的电活化面积均得到明显提高,其中以层层修饰制备的聚溴甲酚绿膜/多壁碳纳米管复合膜(PBG/MWNT/GC)电极最能发挥MWNT和PBG的电活性。将电极用于8-羟基喹啉(8-HQ)电化学行为的研究,结果表明:4种修饰电极的伏安响应明显提高,且8-HQ在PBG/MWNT/GC上的氧化峰电位负移最多,峰电流最大,约为裸玻碳电极的4.5倍,电催化作用显著增强。8-HQ在PBG/MWNT/GC上电极反应的电子转移数和质子数均为1,是吸附控制的不可逆电氧化过程,氧化峰电流Ip与浓度c在4.0×10-6～3.5×10-4mol/L范围内呈良好的线性关系,r=-0.997 2,检出限(S/N=3)为1.96×10-8mol/L。PBG/MWNT/GC修饰电极可实现8-HQ的快捷、简便测定。     

碳纳米管修饰电极上沙丁胺醇电催化氧化研究

将多壁碳纳米管(MWNT)分散在疏水性表面活性剂双十六烷基磷酸(DHP)溶液中形成稳定、均相的分散液,然后制备多壁碳纳米管-DHP复合膜修饰玻碳电极(MWNT-DHP/GCE).应用方波伏安法研究了沙丁胺醇在修饰电极上的电化学行为,结果表明,碳纳米管复合膜修饰电极对沙丁胺醇的氧化有良好的电催化活性,其氧化反应为一电子一质子过程,氧化电位比裸玻碳电极负移40 mV,峰电流增加了4.5倍.在最佳测试条件下,氧化峰电流与沙丁胺醇浓度在8.3×10-7~3.3×10-6mol/L范围内呈良好线性关系,开路富集2min,检出限达1.8×10-7mol/L.该修饰电极具有良好的重现性、稳定性.     

PMB/n-ZnS修饰碳糊电极对双酚A的电化学行为研究

将纳米硫化锌(n-Zn S)作为载体,通过掺杂-电聚合的方式制备出聚亚甲基蓝/纳米硫化锌复合膜修饰电极(PMB/n-Zn S/CPE)。运用循环伏安法(CV)和电子扫描显微镜(SEM)对复合膜进行表征,其元素组成借助于X射线能谱仪(EDS)进行了分析,进而研究了双酚A在该修饰电极上的电化学行为,探讨了最佳实验条件。掺杂了n-Zn S颗粒后的复合膜呈现出三维空间结构,对双酚A的电催化氧化性能显著提高,峰电流是裸电极上的2.5倍,其氧化峰电流与浓度在1.0×10-5~5.0×10-4mol/L范围内呈现出良好的线性关系,检出限为1.0×10-6mol/L。     

乙萘酚在聚N,N-二甲基苯胺/多壁碳纳米管修饰电极上的电化学行为研究

研究了乙萘酚在不同修饰电极上的电化学行为。结果表明:以层层修饰的聚N,N-二甲基苯胺/多壁碳纳米管修饰电极(PDMA/MWNT/GCE)对乙萘酚的电化学响应最佳。在pH为4.86的HAc-NaAc溶液中,乙萘酚在PDMA/MWNT/GCE上是电子数和质子数均为1的扩散控制不可逆电氧化过程,其氧化峰电流与浓度在3.0×10-6～3.0×10-4 mol/L范围内呈良好的线性关系,相关系数R为-0.9958,检出限为2.0×10-6 mol/L,样品测定回收率在94.47%～104.60%之间。     

去甲肾上腺素和抗坏血酸在导电聚合物膜修饰电极上的同时测定

采用循环伏安法研究去甲肾上腺素(NE)和抗坏血酸(AA)在4-(2-吡啶偶氮)间苯二酚(PAR)导电聚合膜修饰电极上的电化学行为;以差示脉冲伏安法(DPV)对二者进行测定,发现PAR修饰电极对NE和AA有很强电催化作用,明显增强了电极反应的可逆性及峰电流。在pH 6.0磷酸盐缓冲液(PBS)中,NE氧化峰电流与其浓度在6.25×10-7~6.25×10-5mol/L范围内呈良好的线性关系,AA氧化峰电流与其浓度在1.0×10-6~3.0×10-4mol/L范围内呈良好的线性关系,检出限分别为5.0×10-8mol/L和5.0×10-7mol/L。该PAR膜修饰电极可对NE和AA进行单独或同时的测定,并用于实际样品重酒石酸去甲肾上腺素针剂和维生素C针剂的检测。     

聚4-氨基丁酸修饰电极的制备及其对多巴胺的测定

应用电聚合的方法以4-氨基丁酸(4-ABA)为修饰剂,将4-ABA聚合在玻碳电极(GCE)表面,制得聚4-氨基丁酸修饰电极(P-4-ABA/GCE),并用于多巴胺(DA)的检测。在pH 5.0的磷酸盐缓冲液(PP)中,DA在0.488V处出现一灵敏的氧化峰,氧化峰电流与DA浓度在9.1×10-8～6.7×10-5mol/L范围内呈现线性关系。检出限为3.0×10-8mol/L。制备的修饰电极,可应用于针剂中多巴胺含量的测定。     

β-丙氨酸-银复合膜修饰电极用于循环伏安法测定对乙酰氨基酚

制备了β-丙氨酸-银复合膜修饰电极(Ag-Ala/GCE),采用循环伏安法研究了对乙酰氨基酚在修饰电极上的电化学行为。结果表明:在pH 4.0的磷酸盐缓冲液中,对乙酰氨基酚在修饰电极上呈现一对灵敏的氧化还原峰,提出了用循环伏安法测定对乙酰氨基酚的含量。对乙酰氨基酚浓度在6.0×10-7～7.0×10-4 mol.L-1范围内与氧化峰电流呈现线性关系,检出限(3S/N)为2.0×10-7 mol.L-1。修饰电极用于药剂中对乙酰氨基酚的测定,并用标准加入法测得方法的回收率在95.1%～101.6%之间。     

Adsorption of carbon dioxide on microporous carbon adsorbents

Adsorption isotherms of carbon dioxide on microporous carbon adsorbents prepared by activation with potassium sulfide in water vapor were measured. The measurements were carried out in the pressure interval from 1 Pa to 0.1 MPa at temperatures from 216.2 to 293.15 K. Based on the theory of volumetric filling of micropores, the main structural and energetic parameters of the microporous carbon adsorbents were calculated. The adsorption isosters of carbon dioxide were calculated from the adsorption isotherms in the same pressure and temperature ranges and approximated by linear dependences. The plots of the differential mole isosteric heats of adsorption vs amount adsorbed were constructed by using the adsorption isosters.     

甲烷在石墨化热解碳黑和活性炭上的吸附

为研究影响碳基吸附剂吸附超临界温度气体的主要因素,选择石墨化热解碳黑BP280和Ajax活性炭,分析超临界温度高压甲烷在其上的吸附平衡。应用容积法,在压力0~20.5 MPa、温度253 K~313 K测定甲烷的吸附平衡数据,并由等量吸附线标绘和亨利定律常数确定等量吸附热。引入通用吸附等温方程,再由方程的Langmuir标绘确定最大吸附容量,进而通过方程的线性化计算吸附平衡态中甲烷分子的作用能。结果表明,甲烷在两种吸附剂上的最大吸附容量均随温度而变化,并都小于液态甲烷的密度;甲烷在碳黑和活性炭上的等量吸附热分别为11.9 kJ/mol~12.5 kJ/mol和17.5 kJ/mol~22.5 kJ/mol,体现了两种吸附剂不同的表面能量分布;甲烷分子间作用能随吸附量的变化特点反映了超临界温度甲烷以类似于压缩气体状态聚集的特点和吸附剂结构上的差异。碳基吸附剂的比表面积和微孔容积是影响其储存甲烷容量的重要因素。     

Adsorption of carbon dioxide on microporous carbon adsorbent PAU-10

Carbon dioxide adsorption on the microporous carbon adsorbent PAU-10 within the 177.8—423 K temperature and 0.1—5.13·10⁶ Pa pressure intervals was studied. The isosteres of absolute adsorption are well approximated by straight lines, which do not change their slope on going to temperatures higher than the critical temperature of CO₂. An increase in the differential molar isosteric heat of adsorption (q _st) at 0 < a < 1 mmol g^–1 is explained by the influence of the endothermic effect of adsorption expansion of the adsorbent. In the region of high pressures and nonideal gas phase, q _st is temperature-dependent.     

Applying diamond like carbon layer on carbon/carbon composites and its effect on the deposition of hydroxyapatite coating

The biomedical application of carbon/carbon (C/C) composites is limited by lacking bioactivity and releasing carbon debris. Hydroxyapatite (HA) coating has been used to improve the bioactivity of C/C composites, but it cannot reduce the release of carbon debris effectively because of poor wear resistance property. In this work, a wear‐resistant layer of diamond like carbon (DLC) is applied on C/C composites, followed by an ultrasound‐assisted electrochemical deposition to prepare HA coatings. The microstructure, morphology and chemical composition of the DLC layer and the HA coating are characterised by scanning electron microscopy, X‐ray diffraction, energy dispersive spectroscopy (EDS), X‐ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy and Raman spectrum. The bonding strength between the HA coating and the DLC layer modified C/C composites is examined by a tensile test. The results show that the DLC layer has a spherical morphology and provides a uniform surface for the deposition of the HA coating. The HA coating shows flaky morphology with a compact structure. The tensile strength of the HA coating on the DLC layer modified C/C composites is 6.24 ± 0.40 MPa, which is significantly higher than that of HA coating on unmodified C/C composites(3.04 ± 0.20 MPa). Copyright © 2013 John Wiley & Sons, Ltd.     

Oxygen reduction on carbon nanomaterial-modified glassy carbon electrodes in alkaline solution

Electroreduction of oxygen in alkaline solution on glassy carbon (GC) electrodes modified with different carbon nanomaterials has been studied. Electrochemical experiments were carried out in 0.1 M KOH employing the rotating disk electrode and rotating ring-disk electrode methods. The GC disk electrodes were modified with carbon nanomaterials using polytetrafluoroethylene as a binder. Four different carbon nanomaterials were used: multiwalled carbon nanotubes, carbon black powder, and two carbide-derived carbons (CDC). For the first time, the electrocatalytic behavior of CDC materials toward oxygen reduction is explored. Electrochemical characterization of the materials showed that all the carbon nanomaterial-modified GC electrodes are highly active for the reduction of oxygen in alkaline solutions.     

多壁碳纳米管-Nafion修饰电极测定左旋氧氟沙星

本文报道了用多壁碳纳米管-Nafion修饰玻碳电极测定痕量左旋氧氟沙星的方法。详细研究了左旋氧氟沙星在修饰电极上的电化学行为。实验表明,该电极对左旋氧氟沙星具有良好的电催化作用。在伏安图中,+1.73V处出现一灵敏氧化峰,利用该峰可进行左旋氧氟沙星的测定。在优化条件下,氧化峰电流与左旋氧氟沙星的浓度在0.001~0.5 mg.mL-1范围内成良好的线性关系。信噪比等于3时,检出限为1×10-4mg.mL-1。用于实际样品中左旋氧氟沙星的测定,加标回收率为97.32~102.82。     

Preparation and characterization of carbon paste micro-electrode based on carbon nanoparticles

The present paper demonstrates the preparation and characterization of micro-electrodes based on carbon paste which is composed of carbon nano-particles with an average diameter of 30 nm and binding oil. The carbon paste electrode material is encased in pulled glass capillaries ranging in diameter from several tens down to less than ten micro-meters (r = 4.5 μm). Manipulation of the carbon paste micro-electrode (CPME) was accomplished via newly developed piston-driven system which construction and related problems are presented. Several parameters influencing the CPME performance including carbon paste composition and its electrochemical activation/preconditioning were investigated. Basic electrochemical behavior and properties were examined using typical redox system, i.e. potassium hexacyanoferrate. Applicability of the proposed carbon paste micro-electrode is illustrated by measuring some potentially interesting organic and inorganic analytes such as dopamine, ascorbic acid and selected heavy metals.